Add ST_Multi

docs/functions.md

@@ -69,6 +69,7 @@
 | [`ST_MakeLine`](#st_makeline) | Creates a LINESTRING geometry from a pair or list of input points |
 | [`ST_MakePolygon`](#st_makepolygon) | Creates a polygon from a shell geometry and an optional set of holes |
 | [`ST_MakeValid`](#st_makevalid) | Attempts to make an invalid geometry valid without removing any vertices |
+| [`ST_Multi`](#st_multi) | Turns a single geometry into a multi geometry. |
 | [`ST_NGeometries`](#st_ngeometries) | Returns the number of component geometries in a collection geometry. |
 | [`ST_NInteriorRings`](#st_ninteriorrings) | Returns the number if interior rings of a polygon |
 | [`ST_NPoints`](#st_npoints) | Returns the number of vertices within a geometry |
@@ -1431,6 +1432,36 @@ Attempts to make an invalid geometry valid without removing any vertices
 
 ----
 
+### ST_Multi
+
+
+#### Signature
+
+```sql
+GEOMETRY ST_Multi (col0 GEOMETRY)
+```
+
+#### Description
+
+Turns a single geometry into a multi geometry.
+
+If the geometry is already a multi geometry, it is returned as is.
+
+#### Example
+
+```sql
+SELECT ST_Multi(ST_GeomFromText('POINT(1 2)'));
+-- MULTIPOINT (1 2)
+
+SELECT ST_Multi(ST_GeomFromText('LINESTRING(1 1, 2 2)'));
+-- MULTILINESTRING ((1 1, 2 2))
+
+SELECT ST_Multi(ST_GeomFromText('POLYGON((0 0, 0 1, 1 1, 1 0, 0 0))'));
+-- MULTIPOLYGON (((0 0, 0 1, 1 1, 1 0, 0 0)))
+```
+
+----
+
 ### ST_NGeometries
 
 

spatial/include/spatial/core/functions/scalar.hpp

@@ -41,6 +41,7 @@ struct CoreScalarFunctions {
 		RegisterStMakeEnvelope(db);
 		RegisterStMakeLine(db);
 		RegisterStMakePolygon(db);
+		RegisterStMulti(db);
 		RegisterStNGeometries(db);
 		RegisterStNInteriorRings(db);
 		RegisterStNPoints(db);
@@ -165,6 +166,9 @@ struct CoreScalarFunctions {
 	// ST_MakePolygon
 	static void RegisterStMakePolygon(DatabaseInstance &db);
 
+	// ST_Multi
+	static void RegisterStMulti(DatabaseInstance &db);
+
 	// ST_NGeometries
 	static void RegisterStNGeometries(DatabaseInstance &db);
 

spatial/src/spatial/core/functions/scalar/CMakeLists.txt

@@ -32,6 +32,7 @@ set(EXTENSION_SOURCES
     ${CMAKE_CURRENT_SOURCE_DIR}/st_makeenvelope.cpp
     ${CMAKE_CURRENT_SOURCE_DIR}/st_makeline.cpp
     ${CMAKE_CURRENT_SOURCE_DIR}/st_makepolygon.cpp
+    ${CMAKE_CURRENT_SOURCE_DIR}/st_multi.cpp
     ${CMAKE_CURRENT_SOURCE_DIR}/st_ngeometries.cpp
     ${CMAKE_CURRENT_SOURCE_DIR}/st_ninteriorrings.cpp
     ${CMAKE_CURRENT_SOURCE_DIR}/st_npoints.cpp

spatial/src/spatial/core/functions/scalar/st_multi.cpp

@@ -0,0 +1,83 @@
+#include "duckdb/common/vector_operations/generic_executor.hpp"
+#include "spatial/common.hpp"
+#include "spatial/core/functions/scalar.hpp"
+#include "spatial/core/functions/common.hpp"
+#include "spatial/core/geometry/geometry.hpp"
+#include "spatial/core/types.hpp"
+#include "spatial/core/geometry/geometry_processor.hpp"
+
+namespace spatial {
+
+namespace core {
+
+//------------------------------------------------------------------------------
+// GEOMETRY
+//------------------------------------------------------------------------------
+
+static void GeometryMultiFunction(DataChunk &args, ExpressionState &state, Vector &result) {
+	auto &lstate = GeometryFunctionLocalState::ResetAndGet(state);
+	auto &arena = lstate.arena;
+	auto &input = args.data[0];
+
+	UnaryExecutor::Execute<geometry_t, geometry_t>(input, result, args.size(), [&](const geometry_t &geom_blob) {
+
+		const bool has_z = geom_blob.GetProperties().HasZ();
+		const bool has_m = geom_blob.GetProperties().HasM();
+
+		switch(geom_blob.GetType()) {
+		case GeometryType::POINT: {
+			auto mpoint = MultiPoint::Create(arena, 1, has_z, has_m);
+			MultiPoint::Part(mpoint, 0) = Geometry::Deserialize(arena, geom_blob);
+			return Geometry::Serialize(mpoint, result);
+		}
+		case GeometryType::LINESTRING: {
+			auto mline = MultiLineString::Create(arena, 1, has_z, has_m);
+			MultiLineString::Part(mline, 0) = Geometry::Deserialize(arena, geom_blob);
+			return Geometry::Serialize(mline, result);
+		}
+		case GeometryType::POLYGON: {
+			auto mpoly = MultiPolygon::Create(arena, 1, has_z, has_m);
+			MultiPolygon::Part(mpoly, 0) = Geometry::Deserialize(arena, geom_blob);
+			return Geometry::Serialize(mpoly, result);
+		}
+		default:
+			return geom_blob;
+		}
+	});
+}
+
+//------------------------------------------------------------------------------
+// Documentation
+//------------------------------------------------------------------------------
+static constexpr const char *DOC_DESCRIPTION = R"(
+	Turns a single geometry into a multi geometry.
+
+	If the geometry is already a multi geometry, it is returned as is.
+)";
+
+static constexpr const char *DOC_EXAMPLE = R"(
+SELECT ST_Multi(ST_GeomFromText('POINT(1 2)'));
+-- MULTIPOINT (1 2)
+
+SELECT ST_Multi(ST_GeomFromText('LINESTRING(1 1, 2 2)'));
+-- MULTILINESTRING ((1 1, 2 2))
+
+SELECT ST_Multi(ST_GeomFromText('POLYGON((0 0, 0 1, 1 1, 1 0, 0 0))'));
+-- MULTIPOLYGON (((0 0, 0 1, 1 1, 1 0, 0 0)))
+)";
+
+static constexpr DocTag DOC_TAGS[] = {{"ext", "spatial"}, {"category", "construction"}};
+
+//------------------------------------------------------------------------------
+// Register functions
+//------------------------------------------------------------------------------
+void CoreScalarFunctions::RegisterStMulti(DatabaseInstance &db) {
+	ScalarFunction function("ST_Multi",{GeoTypes::GEOMETRY()}, GeoTypes::GEOMETRY(), GeometryMultiFunction);
+	function.init_local_state = GeometryFunctionLocalState::Init;
+	ExtensionUtil::RegisterFunction(db, function);
+	DocUtil::AddDocumentation(db, "ST_Multi", DOC_DESCRIPTION, DOC_EXAMPLE, DOC_TAGS);
+}
+
+} // namespace core
+
+} // namespace spatial

test/sql/geometry/st_multi.test

@@ -0,0 +1,21 @@
+require spatial
+
+query I
+SELECT ST_Multi(ST_GeomFromText('POINT(1 2)'));
+----
+MULTIPOINT (1 2)
+
+query I
+SELECT ST_Multi(ST_GeomFromText('LINESTRING(1 1, 2 2)'));
+----
+MULTILINESTRING ((1 1, 2 2))
+
+query I
+SELECT ST_Multi(ST_GeomFromText('POLYGON((0 0, 0 1, 1 1, 1 0, 0 0))'));
+----
+MULTIPOLYGON (((0 0, 0 1, 1 1, 1 0, 0 0)))
+
+query I
+SELECT ST_Multi(ST_GeomFromText('POINT EMPTY'));
+----
+MULTIPOINT (EMPTY)